The market for electronic devices continually demands higher performance at lower costs. In order to meet these requirements, the components which comprise various electronic devices need to be made more efficiently and to closer tolerances.
One type of electronic device is a fluid ejection device that ejects fluid via one or more orifices. In certain types of fluid ejection devices, a fluid feed channel or slot is formed to feed fluid to chambers in which the fluid is heated and ejected via the one or more orifices. In order to be able to eject fluid in a timed a precise matter, slot or channel needs to be aligned within certain tolerances.
In some embodiments, the slot is formed in the substrate by wet chemical etching of the substrate with, for example, Tetra Methyl Ammonium Hydroxide (TMAH) or potassium hydroxide (KOH). The etch rate for alkaline chemistries is different for different crystalline planes, and therefore the etch geometry is defined by the orientation of the crystalline planes. For example, on {100} substrates, TMAH etching techniques result in etch angles that cause a very wide backside slot opening. The wide backside opening limits how close the slots can be placed to each other on the die.
In addition, in many fluid ejection devices, different fluid passages should be aligned with each other in order to prevent potential damage to the fluid ejection device and to maintain proper operation. In some cases, slots or trenches within a fluid ejection device that are not properly aligned can lead to chipping of substrate material that can clog other fluid passage ways thereby damaging or making non-functional the fluid ejection device.
Therefore, It is desired to efficiently align slots or trenches in a substrate within desired dimensional tolerances.